import file_access_module = require("FileSystem/file_system_access");

export module tk {
    export module io {
        // The FileSystemAccess implementation, used through all the APIs.
        var fileAccess;
        var getFileAccess = function (): file_access_module.tk.io.FileSystemAccess {
            if (!fileAccess) {
                fileAccess = new file_access_module.tk.io.FileSystemAccess();
            }

            return fileAccess;
        }

        // we are defining these as private variables within the IO scope and will use them to access the corresponding properties for each FSEntity instance.
        // this allows us to encapsulate (hide) the explicit property setters and force the users go through the exposed APIs to receive FSEntity instances.
        var nameProperty = "_name";
        var pathProperty = "_path";
        var isKnownProperty = "_isKnown";
        var fileLockedProperty = "_locked";
        var extensionProperty = "_extension";
        var readonlyProperty = "_readonly";
        var lastModifiedProperty = "_lastModified";

        /**
          * Represents the basic file system entity - a File or a Folder.
          */
        export class FileSystemEntity {
            /**
              * Gets the Folder object representing the parent of this entity. Will be null for a root folder like Documents or Temporary.
              */
            public getParent(onSuccess: (parent: Folder) => any, onError?: (error: any) => any) {
                var localSuccess = function (path: string) {
                    var folder = new Folder();
                    folder[pathProperty] = path;

                    if (onSuccess) {
                        onSuccess(folder);
                    }
                }
                getFileAccess().getParent(this.path, localSuccess, onError);
            }
            /**
              * Deletes the current entity from the file system.
              */
            public delete(onSuccess?: () => any, onError?: (error: any) => any) {
                if (this instanceof File) {
                    getFileAccess().deleteFile(this.path, onSuccess, onError);
                } else if (this instanceof Folder) {
                    getFileAccess().deleteFolder(this.path, this[isKnownProperty], onSuccess, onError);
                }
            }
            /**
              * Renames the current entity using the specified name.
              */
            public rename(newName: string, onSuccess?: () => any, onError?: (error: any) => any) {
                // TODO: No implementation
            }
            /**
              * Gets the name of the entity.
              */
            get name(): string {
                return this[nameProperty];
            }
            /**
              * Gets the fully-qualified path (including the extension for a File) of the entity.
              */
            get path(): string {
                return this[pathProperty];
            }
            /**
              * Gets a value indicating whether this entity is read-only (no write persmissions).
              */
            get readonly(): boolean {
                var value = this[readonlyProperty];
                if (this[readonlyProperty] === undefined) {
                    value = this[readonlyProperty] = getFileAccess().getReadonly(this.path);
                }

                return value;
            }
            /**
              * Gets the fully-qualified path (including the extension for a File) of the entity.
              */
            get lastModified(): Date {
                var value = this[lastModifiedProperty];
                if (this[lastModifiedProperty] === undefined) {
                    value = this[lastModifiedProperty] = getFileAccess().getLastModified(this.path);
                }

                return value;
            }
        }

        /**
          * Represents a File entity.
          */
        export class File extends FileSystemEntity {
            /**
              * Gets the File instance associated with the specified path.
              */
            public static fromPath(path: string, onSuccess: (file: File) => any, onError?: (error: any) => any) {
                var localSuccess = function (path: string) {
                    var file = new File();
                    file[pathProperty] = path;

                    if (onSuccess) {
                        onSuccess(file);
                    }
                }
                getFileAccess().getFile(path, localSuccess, onError);
            }
            /**
              * Checks whether a File with the specified path already exists.
              */
            public static exists(path: string): boolean {
                return getFileAccess().fileExists(path);
            }
            /**
              * Deletes the current File from the file system.
              */
            public delete(onSuccess?: () => any, onError?: (error: any) => any) {
                getFileAccess().deleteFile(this.path, onSuccess, onError);
            }
            /**
              * Creates a FileReader object over this file and locks the file until the reader is released.
              */
            public openRead(): FileReader {
                this.checkAccess();
                return new FileReader(this);
            }
            /**
              * Creates a FileWriter object over this file and locks the file until the writer is released.
              */
            public openWrite(): FileWriter {
                this.checkAccess();
                return new FileWriter(this);
            }
            /**
              * Gets the extension of the entity.
              */
            get extension(): string {
                return this[extensionProperty];
            }
            /**
              * Gets a value indicating whether the file is currently locked, meaning a background operation associated with this file is running.
              */
            get isLocked(): boolean {
                return this[fileLockedProperty];
            }

            private checkAccess() {
                if (this.isLocked) {
                    throw {
                        message: "Cannot access a locked file."
                    };
                }
            }
        }

        /**
          * Represents a Folder entity.
          */
        export class Folder extends FileSystemEntity {
            /**
              * Attempts to access a Folder at the specified path and creates a new Folder if there is no existing one.
              */
            public static fromPath(path: string, onSuccess: (folder: Folder) => any, onError?: (error: any) => any) {
                var localSuccess = function (path: string) {
                    var folder = new Folder();
                    folder[pathProperty] = path;

                    if (onSuccess) {
                        onSuccess(folder);
                    }
                }
                getFileAccess().getFolder(path, localSuccess, onError);
            }

            /**
              * Checks whether a Folder with the specified path already exists.
              */
            public static exists(path: string): boolean {
                return getFileAccess().folderExists(path);
            }

            /**
              * Checks whether this Folder contains a file with the specified name.
              */
            public containsFile(name: string): boolean {
                var fileAccess = getFileAccess();
                var path = fileAccess.concatPath(this.path, name);
                return fileAccess.fileExists(path);
            }

            /**
              * Deletes the current Folder (recursively) from the file system.
              */
            public delete(onSuccess?: () => any, onError?: (error: any) => any) {
                getFileAccess().deleteFolder(this.path, this.isKnown, onSuccess, onError);
            }

            /**
              * Deletes all the files and folders (recursively), contained within this Folder.
              */
            public empty(onSuccess?: () => any, onError?: (error: any) => any) {
                getFileAccess().emptyFolder(this.path, onSuccess, onError);
            }

            /**
              * Determines whether this instance is a KnownFolder (accessed through the KnownFolders object).
              */
            get isKnown(): boolean {
                return this[isKnownProperty];
            }

            /**
              * Attempts to open a File with the specified name within this Folder and optionally creates a new File if there is no existing one.
              */
            public getFile(name: string, onSuccess: (file: File) => any, onError?: (error: any) => any, createIfNonExisting?: boolean) {
                var localSuccess = function (filePath: string) {
                    var newFile = new File();

                    newFile[pathProperty] = filePath;
                    newFile[nameProperty] = name;

                    if (onSuccess) {
                        onSuccess(newFile);
                    }
                }
                var fileAccess = getFileAccess();
                var path = fileAccess.concatPath(this.path, name);
                fileAccess.getFile(path, localSuccess, onError);
            }

            /**
              * Attempts to open a Folder with the specified name within this Folder and optionally creates a new Folder if there is no existing one.
              */
            public getFolder(name: string, onSuccess: (folder: Folder) => any, onError?: (error: any) => any) {
                var localSuccess = function (filePath: string) {
                    var newFolder = new Folder();

                    newFolder[pathProperty] = filePath;
                    newFolder[nameProperty] = name;

                    if (onSuccess) {
                        onSuccess(newFolder);
                    }
                }

                var fileAccess = getFileAccess();
                var path = fileAccess.concatPath(this.path, name);
                fileAccess.getFolder(path, localSuccess, onError);
            }

            /**
              * Gets all the top-level files residing within this Folder.
              */
            public enumFiles(onSuccess: (files: Array<File>) => any, onError?: (error: any) => any) {
                var localSuccess = function (paths: Array<string>) {
                    if (onSuccess) {
                        var files = new Array<File>();
                        var i,
                            path: string,
                            file: File;

                        for (i = 0; i < files.length; i++) {
                            file = new File();
                            file[pathProperty] = files[i];
                            files.push(file);
                        }

                        onSuccess(files);
                    }
                }
                getFileAccess().enumFiles(this.path, localSuccess, onError);
            }
        }

        /**
          * Provides access to the top-level Folders instances that are accessible from the application. Use these as entry points to access the FileSystem.
          */
        export class KnownFolders {
            private static _documents: Folder;
            private static _temp: Folder;

            /**
              * Gets the Documents folder available for the current application. This Folder is private for the application and not accessible from Users/External apps.
              */
            public static Documents(): Folder {
                if (!KnownFolders._documents) {
                    var path = getFileAccess().getDocumentsFolderPath();
                    KnownFolders._documents = new Folder();
                    KnownFolders._documents[pathProperty] = path;
                    KnownFolders._documents[isKnownProperty] = true;
                }

                return KnownFolders._documents;
            }

            /**
              * Gets the Temporary (Caches) folder available for the current application. This Folder is private for the application and not accessible from Users/External apps.
              */
            public static Temporary(): Folder {
                if (!KnownFolders._temp) {
                    var path = getFileAccess().getTempFolderPath();
                    KnownFolders._temp = new Folder();
                    KnownFolders._temp[pathProperty] = path;
                    KnownFolders._temp[isKnownProperty] = true;
                }

                return KnownFolders._temp;
            }
        }

        /**
          * Base class for FileReader and FileWriter APIs.
          */
        export class FileAccess {
            private _file;

            constructor(file: File) {
                this._file = file;
                this._file[fileLockedProperty] = true;
            }

            /**
              * Unlocks the file and allows other operations over it.
              */
            public release() {
                this._file[fileLockedProperty] = false;
                this._file = undefined;
            }

            /**
              * Gets the underlying File instance.
              */
            get file(): File {
                return this._file;
            }
        }

        /**
          * Enables reading the content of a File entity.
          */
        export class FileReader extends FileAccess {
            /**
              * Reads the content of the underlying File as a UTF8 encoded string.
              */
            public readText(onSuccess: (content: string) => any, onError?: (error: any) => any) {
                getFileAccess().readText(this.file.path, onSuccess, onError);
            }
        }

        /**
          * Enables saving data to a File entity.
          */
        export class FileWriter extends FileAccess {
            public writeText(content: string, onSuccess?: () => any, onError?: (error: any) => any) {
                getFileAccess().writeText(this.file.path, content, onSuccess, onError);
            }
        }
    }
}